The invention disclosed relates to an apparatus for the automatic separation of stacked sheets of large format paper into reams, and for subsequent transfer of the reams to wrapping machinery.
In the art field embracing the manufacture of paper in reams of large format sheets for designers, artists etc., a problem typically encountered with the wrapping operation is that of how the reams are fed to the wrapping machine.
Reams destined for wrapping by the machine are discharged by the sheeter onto a pallet in a simple stack of single sheets; the pallet is placed on an elevator platform which ascends automatically every time the operator removes a ream, in such way that handling occurs at an unvarying height.
Substantially two basic conventional methods are used for separating the stack of sheets into reams.
The first such method is extremely precise. The stack of sheets from which the reams are formed is prepared by a machine that counts off the sheets and inserts a marker between one sheet and the next each time the count is completed; the marker is nothing other than a piece of paper or some other material, colored or otherwise, that protrudes from the stack, and the operator simply lifts off the stacked sheets that lie above the marker and supplies them to the wrapping machine.
The second method makes use of an instrument similar to a gage, with two measuring arms, one of which is fixed and provided with a locator, the other mobile and fitted with a blade designed to penetrate between adjacent sheets. The operator calculates the depth of the ream on the basis of the number and the thickness of the single sheets, then, offering the fixed locating arm to the top sheet, slides the gage foward to the point where the blade inserts between two sheets at the selected depth, and thus separates the ream from the remainder of the stack beneath.
This second method is basically sound, but tends to be insufficiently accurate as a result of being dependent on a number of factors, e.g. the moisture content and the thickness of the sheets.
Thin sheets ensure greater precision, since the blade of the instrument can slip more easily between them; on the other hand, the blade can dig into the edge of a thicker product, such as cartridge paper.
An additional factor tending to compromise the accuracy of this second method is the height of the stack of sheets; more exactly, the topmost ream to be separated will be of a certain depth, but this depth will reduce as the stack gradually diminishes, by dint of the fact that the sheets lower down are compressed and compacted permanently by the weight of the sheets above.
At all events, separation of the stack of sheets into reams, in either of the methods thus described, remains a manually-implemented process.
Accordingly, the object of the invention is to provide an apparatus capable of receiving a stack of sheets and separating it into reams automatically, then of supplying the reams to the infeed station of a wrapping machine, likewise automatically.
A further object of the invention is to embody an apparatus that will be capable of achieving this main object in an economical and functional manner.